From 51016670a24092b6b9ecd0f50d1aaa976e780cc1 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Tue, 4 May 2021 23:06:50 +0200
Subject: General fixes (see description) - closes #17

Somehow the Grub conversion (or anything before/between that) seems
to have caused a *very* weird memory bug involving the heap/stack/sth
overflowing into the video memory which will obviously result in strange
undefined behaviour when data is written to the video memory.

VERY STRANGE. Well, I need to prepare for my finals (Abitur) so I don't know
whether I can fix this issue in the next few days. We'll see...
---
 kernel/drivers/fb.c  | 14 ++++++--------
 kernel/features/mm.c |  1 +
 kernel/inc/proc.h    |  2 +-
 3 files changed, 8 insertions(+), 9 deletions(-)

(limited to 'kernel')

diff --git a/kernel/drivers/fb.c b/kernel/drivers/fb.c
index 8831a52..8122654 100644
--- a/kernel/drivers/fb.c
+++ b/kernel/drivers/fb.c
@@ -12,6 +12,8 @@
 #include <str.h>
 #include <sys.h>
 
+#define FB_SIZE (vbe->height * vbe->pitch)
+
 struct vbe_basic {
 	u8 stuff1[16];
 	u16 pitch;
@@ -27,8 +29,7 @@ PROTECTED static struct vbe_basic *vbe = NULL;
 static u32 fb_map_buffer(struct page_dir *dir)
 {
 	assert(vbe);
-	u32 size = vbe->height * vbe->pitch;
-	return virtual_alloc(dir, memory_range_around((u32)vbe->fb, size), MEMORY_USER).base;
+	return virtual_alloc(dir, memory_range_around((u32)vbe->fb, FB_SIZE), MEMORY_USER).base;
 }
 
 static u32 fb_owner = 0;
@@ -48,8 +49,7 @@ static res fb_ioctl(u32 request, void *arg1, void *arg2, void *arg3)
 
 		if (fb_owner != 0 && proc_from_pid(fb_owner))
 			return -EBUSY;
-		else
-			fb_owner = proc_current()->pid;
+		fb_owner = proc_current()->pid;
 
 		u32 fb = fb_map_buffer(proc_current()->page_dir);
 		vbe->fb = (u8 *)fb;
@@ -69,8 +69,6 @@ CLEAR void fb_install(void)
 	dev->control = fb_ioctl;
 	io_add(IO_FRAMEBUFFER, dev);
 
-	// Identity map framebuffer to kernel to prevent unwanted writing
-	u32 size = vbe->height * vbe->pitch;
-	memory_map_identity(virtual_kernel_dir(), memory_range_around((u32)vbe->fb, size),
-			    MEMORY_CLEAR);
+	// Set framebuffer range used to prevent unwanted writing
+	physical_set_used(memory_range_around((u32)vbe->fb, FB_SIZE));
 }
diff --git a/kernel/features/mm.c b/kernel/features/mm.c
index e60e2b5..7a39b33 100644
--- a/kernel/features/mm.c
+++ b/kernel/features/mm.c
@@ -136,6 +136,7 @@ static void physical_page_set_free(u32 address)
 
 CLEAR void physical_set_total(u32 total)
 {
+	assert(total > 0);
 	memory_total = total;
 }
 
diff --git a/kernel/inc/proc.h b/kernel/inc/proc.h
index 000d77d..242a8d4 100644
--- a/kernel/inc/proc.h
+++ b/kernel/inc/proc.h
@@ -10,7 +10,7 @@
 #include <sys.h>
 
 #define PROC_QUANTUM 42 // Milliseconds or something // TODO
-#define PROC_STACK_SIZE (1 << 20) // 1MiB
+#define PROC_STACK_SIZE 0x4000 // 16KiB
 
 #define EFLAGS_ALWAYS 0x2 // Always one
 #define EFLAGS_INTERRUPTS 0x200 // Enable interrupts
-- 
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